In this paper we discuss the effects of deslagging practices and the size of electric arc furnace (EAF) slags on structural, microstructural, composition and leaching tests. The samples were collected from seven steelmakers located in Brescia (Lombardy Region, Italy). Nine granularity fractions of four samples were tested to evaluate the influence of the granularity on the leaching tests. The results showed that, in general, the release of the elements arises when the size of the particle decreases, except in one sample, in which vanadium and zinc displayed the opposite trend. X-ray diffraction results suggest that behavior may be ascribed to the effect of the grinding, which causes a different percentage of the phases in the various fractions. In conclusion, the possible effects of the size should also be carefully considered when defining new leaching test requirements for EAF slags.
31 January 2019 in The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences
This work aims at presenting the use of new technologies in the field of forensic engineering. In particular, the use of UAV photogrammetry and laser scanning is compared with the traditional methods of surveying an accident site. In this framework, surveys must be carried out promptly, executed in a short time and performed so that the greatest possible amount of information is collected with sufficient accuracy to avoid the possibility of neglecting details once that the scene is no longer preserved. The combination of modern surveying techniques such UAV photogrammetry and laser scanning can properly fulfill these requirements. An experimental test has been arranged and instruments, procedures, settings, practical limits and results have been evaluated and compared with respect to the usual way of performing the survey for forensic purposes. In particular, both qualitative and quantitative considerations are given, assessing the completeness of the reconstructed model, the statistical evaluation of the errors and the accuracy achieved.
Electric arc furnace (EAF) slags were investigated by micro-Raman spectroscopy. A slag sample characterised by well-developed crystalline phases was obtained. The EDXS elemental composition made it possible to recognize the grains corresponding to the brownmillerite, larnite and magnesioferrite phases, as identified by XRD in the same powdered sample. The grains were collected and analysed by µ-Raman spectra, and the results showed good reproducibility in each grain and good agreement with spectra of the phases reported in the literature. A Raman database devoted to crystalline phases of EAF slag identification was created to be used by portable Raman instruments, allowing the phase characterisation of the slag directly during steel production.
This work tackles the methodological challenge of rationalizing symmetric‐cell cycling data from a materials‐science perspective, through experiment replication, mathematical modelling, and tomographic imaging. Specifically, we address Zn electrode cycling in alkaline electrolyte with and without adding tetrabutylammonium bromide (TBAB). This additive is known from literature, but its practical impact is jeopardized by lack of in‐depth understanding of its behaviour. Electrochemical testing was carried out at practically relevant current densities and the effect of variations of operating conditions was taken into account. The physical chemistry underlying cell potential profiles, has been modelled mathematically, accounting for: electrokinetics, mass‐transport, electrode shape change and passivation. In particular, we disclosed an unexpected joint effect of TBAB and current density on passivation time: tomography allowed to rationalise this behaviour in terms of precipitate morphology.